There isn't one license agreement that covers all my fonts; the agreement varies from distributor to distributor. Always refer to the agreement that came with the fonts. If the fonts didn't come with an agreement, you should track down a new version.

Desktop license

Sometimes you'll hear the term "desktop license". It means you download the font, install it in Windows, OSX or whatever and use it in applications to make stuff. While there are some differences between desktop license agreements, there are some things they always allow.
A desktop license will always allow you to use the fonts to make logos, web graphics, business cards, t-shirts, posters and signs. You can use them in paper books and magazines. You can use them in movies and television. You can embed them in PDF documents in non-editable mode.

Free vs. not-free

There's no difference between a license agreements for free fonts or "pay" fonts. The same commercial use is allowed.

Web, apps & eBooks

License agreements have restrictions about embedding. If you're not embedding, the desktop license will cover it. If you're embedding, it probably requires a different type of license. More on embedding here.